1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
8 * Title: arm_cfft_radix4_init_q31.c
10 * Description: Radix-4 Decimation in Frequency Q31 FFT & IFFT initialization function
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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15 * modification, are permitted provided that the following conditions
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20 * notice, this list of conditions and the following disclaimer in
21 * the documentation and/or other materials provided with the
23 * - Neither the name of ARM LIMITED nor the names of its contributors
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25 * software without specific prior written permission.
27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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39 * -------------------------------------------------------------------- */
42 #include "arm_common_tables.h"
45 * @ingroup groupTransforms
49 * @addtogroup ComplexFFT
55 * @brief Initialization function for the Q31 CFFT/CIFFT.
56 * @param[in,out] *S points to an instance of the Q31 CFFT/CIFFT structure.
57 * @param[in] fftLen length of the FFT.
58 * @param[in] ifftFlag flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.
59 * @param[in] bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
60 * @return The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if <code>fftLen</code> is not a supported value.
64 * The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.
65 * Set(=1) ifftFlag for calculation of CIFFT otherwise CFFT is calculated
67 * The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.
68 * Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.
70 * The parameter <code>fftLen</code> Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.
72 * This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
75 arm_status
arm_cfft_radix4_init_q31(
76 arm_cfft_radix4_instance_q31
* S
,
79 uint8_t bitReverseFlag
)
81 /* Initialise the default arm status */
82 arm_status status
= ARM_MATH_SUCCESS
;
83 /* Initialise the FFT length */
85 /* Initialise the Twiddle coefficient pointer */
86 S
->pTwiddle
= (q31_t
*) twiddleCoefQ31
;
87 /* Initialise the Flag for selection of CFFT or CIFFT */
88 S
->ifftFlag
= ifftFlag
;
89 /* Initialise the Flag for calculation Bit reversal or not */
90 S
->bitReverseFlag
= bitReverseFlag
;
92 /* Initializations of Instance structure depending on the FFT length */
95 /* Initializations of structure parameters for 4096 point FFT */
97 /* Initialise the twiddle coef modifier value */
98 S
->twidCoefModifier
= 1u;
99 /* Initialise the bit reversal table modifier */
100 S
->bitRevFactor
= 1u;
101 /* Initialise the bit reversal table pointer */
102 S
->pBitRevTable
= (uint16_t *) armBitRevTable
;
105 /* Initializations of structure parameters for 1024 point FFT */
107 /* Initialise the twiddle coef modifier value */
108 S
->twidCoefModifier
= 4u;
109 /* Initialise the bit reversal table modifier */
110 S
->bitRevFactor
= 4u;
111 /* Initialise the bit reversal table pointer */
112 S
->pBitRevTable
= (uint16_t *) & armBitRevTable
[3];
116 /* Initializations of structure parameters for 256 point FFT */
117 S
->twidCoefModifier
= 16u;
118 S
->bitRevFactor
= 16u;
119 S
->pBitRevTable
= (uint16_t *) & armBitRevTable
[15];
123 /* Initializations of structure parameters for 64 point FFT */
124 S
->twidCoefModifier
= 64u;
125 S
->bitRevFactor
= 64u;
126 S
->pBitRevTable
= (uint16_t *) & armBitRevTable
[63];
130 /* Initializations of structure parameters for 16 point FFT */
131 S
->twidCoefModifier
= 256u;
132 S
->bitRevFactor
= 256u;
133 S
->pBitRevTable
= (uint16_t *) & armBitRevTable
[255];
137 /* Reporting argument error if fftSize is not valid value */
138 status
= ARM_MATH_ARGUMENT_ERROR
;
146 * @} end of ComplexFFT group